Discharge vessel cooled by radiation



J. E. SCHEEL 2,909,702

DISCHARGE VESSEL COOLED BY RADIATION 2 Shets-Sheec 1 Oct. 20,, 1959Filed May 20, 1955 J. E. SCHEEL DISCHARGE VESSEL COOLED BY RADIATIONOct. 20, 1959 2 Sheets-Sheet 2 Filed May 20, 1955 ,ifoachim Eric Scheel,Ettlingen, Baden, Germany, as-

metricdesilgh of the cathode itself or its coating, in

this kind of tubes. I The invention provides an anode in which areformed States Patent Ofiice 2,909,702 Patented Oct. 20, 1959 2,9 09,7o2DISCHARGE-VESSEL COOLED BY RADIATION Signor to Siemens & HalskeAktiengesellschaft, Munich and Berlin, Germany, a corporation of GermanyApplication May 20, 1955, Serial No. 509,930

In Germany October 1, 1948v Public Law 619, August 23, 1954 Patentexpires October 1, 1968 v This invention relatesto a discharge vessel cod y radiation.

The invention is particularly concerned with a discharge tube in' whichmay be expected strong heating of the anodes at which the work load isconverted into heat due to the bombarding electron flow. In dischargetubes with radiation-cooled anodes, the cooling fin principle has beenused untilnow, that is, cooling fins or ribs have been provided forconducting and radiating the heat away outwardly. M

The invention proposes a new way of radiation cooling I of such -anodesand is of' particular importance in connection vwith relatively highcapacity discharge tubes provided with,indirectly heated cathodesof'relatively'low operating temperature; for example, oxide' cathodes. Suchtubesare usually customary tubes with centrally disposed cathode of asystem of several individual cathodes. About the cathode are arrangedthe individual electrodes among which may be one or morecontrol'electrodes (grids), forming an inner system. One. or'fmore ofthese'la'tte'r electrodes mayeifect bunching or separatio ,re pectivelyfof the electron stream emanating from the cathode Separation ordistribution of f the cathode streamer flow may also be effected bythegeo- 40 sectors, with an'emitting substance, alone or in cooperationwith the action of the 'electrodes of the inner system.

This is the reason for referring to electron fiow from the cathode tothe anode as taking place 'in diiferent flow sector-s. -'-The inventionis of particular importance for two or more recesses-for individualelectron flow sectors or for each flow sector emanating from the innersystem, the'entire or atleast the prepondera'n't portion of the electronflow energy being converted into heat at the inner surfaces ofsaid'recesses. The recesses are thereby suitably so designed that theyproject outwardly for relatively considerable distances and exhibitlarge interior surfaces ex- -tending at very acute angles to thedirection of the elec- .tron' flow. Depending upon the design of theelectrode system and the entire tube, it may be suitable to provide therecesses with their longitudinal extent and their aperture slots inparallel to the longitudinal axis of'th'e inner electrode system. Thearrangement may otherwise be such that the recesses extend perpendicularthereto,

that is, with the aperture slotsarranged, for example, annularly orhelically sector-likeabout the longitudinal axis of the inner electrodesysteml -Theindividual recesses may also be formed differently, forexample, cone-shaped 5 or in pyramid form. -A stretched form may in somecases be desirable so as to result in wedge-shaped forma- I tion withblunt or pointed ends. A plurality of recesses for a flow sectormay bedisposed one directlynext to ..the other or one underneath the other,basesof two adjacent recesses merging The depthoffthe individualrecesses may be substantially with the aperture 7 into oneanother.

V pyramid shape, projecting in the manner of thorns or barbs from theanode surface proper. It will, of course, be easier, for manufacturingreasons, not to provide a multitude of individual protuberances butalways a series thereof in the form of striplike elevations or the like.

The-various objects and features of the invention will appear from thedescription which will be rendered below with reference to theaccompanying diagrammatic drawings, wherein Figfl shows in schematicsectional view parts of a known tube system;

Fig, 2 shows a similar system comprising cooling recesses; Figs. 3, 4,5a and 511 different shape; and o Fig; 6"s'hows a furtherembodiment Fig.1, showing a symmetrically designed discharge system of which onlyone-half is represented, comprises a centrally disposed cathode 1, whichmay be, for examshow systemsv with. recesses of "ple, an indirectlyheated oxide cathode. The-electron emitting coating is provided upon theoval surfaces of the cathode 1. Two electrodes 2 and 3 embrace thecathode slightly spaced therefrom. These electrodes may actas a firstand a second grid of a discharge tube oper- .ating' as a'pseudo pentode(tetrode). Two metallic members 4;which are at cathode potential, limitthe flow space, so that dischargesectors are formed respectivelyupwardly and in not illustrated fashion also downwardly. These metallicmembers '4 effect so to speak a focusing and,

being at cathode potential, may be considered a rudimentary suppressiongrid. Numerals 5 and 6 indicate the anode or plate which is in knownmanner formed in accordance with' the. cooling fin principle. Theelectron flow penetrating the inner tube system arrives at therelatively small inner plate surfaces 5 which are disposed more or lesscoaxial therewith, and the heat produced there is conducted with acorresponding temperature drop to theradiating cooling fins 6.

The realization of this principle leads especially in high capacitytubes to relatively heavy anodes made of thick material with numerouscooling fins some of which may extend perpendicular to the surfaces 6.The selection of the anode material is limited to anode material withthe required heat conductivity over the small cooling fin cross-sectionin longitudinal direction of the corresponding surfaces. The cooling ofthe anode causes difliculties in allknown arrangements of this kind.

The invention'proceeds from the recognition of the observation that thecause of these difiiculties liesprimarilyin the fact that a part of theanode, in the known arrangements, absorbs heat, as is the case with thesurfaces'5, while the other parts (surfaces 6) serve solely for givingoff heat. It is in this connection immaterial whether or not grooves arebeing pressedinto the anode sheets of the known arrangements. 'In allthese cases, the -preponderant part of the electron flow is caught bythe coaxial inner surfaces 5 of the plates, such plates embracing theinner system with narrowest spacing and highest 'platetemperature'andthus adversely afiecting the heat stability of thesystem. Special measures must oftentimes be taken in order to prevent inthe case of oxide cathodes, an undesired thermal emission of the gridsneighboring the cathode. The unfavorable ratio between production costsand expenditure and weight and obtainable results with cooling finanodes leads in high capacity tubes above all to larger structuraldimensions than would v.be either necessary or suitable without theselimitations.

As compared with these known constructions, the invention makes itpossible to design the anode so that the same surfaces which are exposedto the heat are also utilized for giving off heat.

In the tube according to the invention, a system of surfaces is beingused, in place of the cooling fin anode indicated in Fig. 1 at 5 and 6,which, which is formed and arranged so that an anode is produced whichis provided with recesses forming openings in the direction of theelectron flow directed thereto. The design of these recesses is inconnection with auxiliary means to be presently described, such, thatthe electron flow is wholly or partially converted into heat at theinner surfaces of the recesses. These inner surfaces may be formed verymuch larger than the relatively small coaxial impact surfaces of thecooling fin anode. The number of recesses, their arrangement, form,depth, aperture, width, etc., depends upon the inner system of the tubeand the operating conditions thereof. This is particularly importantwhen great load densities are to be coped with, as they occur, forexample, with indirectly heated cathodes as electron flow sources.

In Fig. 2 is shown an embodiment, in schematic sectional view, whichcorresponds in essential details very much to the known structure shownin Fig. 1. The inner system has the identical electrode structures 1, 2,3, 4, having however instead of the cooling fin anode 5, 6 of Fig. 1, ananode in which are formed recesses, 8 defined by sloping walls 7.Similar to Fig. 1, only the upper half of the system is being shown inFig. 2, comprising three recesses 8 with apertures for the incomingupper electron flow sector lying relatively to the inner systemextending approximately coaxial thereto. The electron flow impactspreponderantly the straight or nicked wall surfaces 7, and its energy isthere converted into heat. The total surface of the walls 7, impacted bythe electron flow, may, in otherwise identical conditions and dependingupon the number, depth and form of the recesses may be increased to amultiple of the impact surfaces 5 of the cooling fin anode of Fig. 1.The inner surfaces formed by the walls 7 alone determines the reflectedheat radiation in the direction of the inner system. The path of theheat from the heat-receiving walls 7 to the outside depends upon thewall thickness and the heat conductivity of the anode material used.

The invention offers in view of this situation the further advantagethat extraordinarily thin and light plates may be made of sheet materialor wire mesh or the like. It is furthermore possible, in view of thethin wall dimensions, to use material with relatively low heatconductivity, thus removing the limitations as to plate material in theselection thereof.

It may be suitable in many cases, to make the recesses dissimilar, asindicated in Fig. 2 by the greater depth and aperture width of themiddlemost recess as compared with the two adjacent recesses, and asalso indicated by the legs 23 and 24. By suitable design of the recessesor their number, the energy of part of the electron flow will beconverted into heat directly at the ends 29 of the recesses, that is,considerably farther away from the inner electrode system as is, underotherwise similar Conditions due to the development of a virtualcathode, possible in the case of anodes provided with cooling fins.

In addition to the radiation advantages obtained, there appear inpentode operation, the advantages of a farreaching suppression of thesecondary emission exchange between the anode and the inner electrodesystem, because the recesses act as cages so far as the potential isconcerned. This in turn gives, for example, the possibility of a greatervariation in the screen grid potential than is possible in an anodeprovided with cooling fins with space charge threshold according to Fig.1.

A good utilization of the anode space is connected with a predeterminedminimum number of recesses per elec* tron flow sector. Accordingly, toeach flow sector,'there is allotted an anode sector with two or morerecesses. The upper anode sector with the three protuberances' 8 shownin Fig. 2 corresponds accordingly to the upper electron flow sector.

The intended effect may if desired be supported potentialwise by apre-anode which may be formed, for example, gridlike, especially of asmall number of highly loadable wires. Such pre-anode is either directlycon nected with the anode or by an electrode 9 which may be combinedtherewith as diagrammatically indicated in Fig. 2. However, a spatiallyseparate pre-anode may be provided.

In the embodiment shown in Fig. 2, it will be impossible to avoid alwaysa strong heating of the aperture legs 23 and 24. In order to obtain alower loading of these legs, other measures may be applied which arediagrammatical ly indicated in Figs. 3, 4, 5a and 5b.

In the embodiment shown in Fig. 3, the upper sector, extending from theinner electrode system 1, 2 and 3, is electron-optically linked with theelectron 'flow directed into two recesses 12 illustrating the upperanode half. For this purpose, there is provided a bar 11 between an odeand grid 3 extending in parallel to the longitudinal axis of the tubesystem in the symmetry plane which projects through the center of thecathode and the common aperture base 13 of the two'anode recesses 12.The bar 11 may be potentialwise connected with the limiting elements 4or may be connected to a separate fixed or functionally dependentpotential.

The limiting elements 4 and the bar 11 as well as by the recess bases 13and 25 form an electron optical lens system. A suitable geometricscheme, preferably in the design in the vicinity of the recess bases 13and 25, in connection with suitable operating potential ranges, willmake it possible to provide for a sufficiently satisfactory electronoptical guidance of the electron flow as well as a potential influencein the anode space resulting there rom.

For this purpose, the base 13 which is common to recesses 12 may be madeconsiderably more rounded and wider than would be tolerable loadwisewith the bases 23 and 24 according to Fig. 2. The more pronouncedrounding at the bases 25 and interiorly of the walls 10, in thedirection of the recess centers, acts in a cooperative supporting mannerand permits a desired surface distribution of the impacting electronflow the energy of which is converted into heat primarily along thewalls 10. The surfaces of the bases '13 and 25 can be held suflicientlyfree of this effect. The design and potential conditions of the bar 11,under some circumstances with the elements 4, may be effected withconsideration of the electron optical properties of the lens system. Thesuppression grid effect thereby additionally occurring, which becomesoperative in predetermined embodiments and under predetermined operatingconditions, and which can be utilized therewith, is for the inventiononly of subsidiary importance.

Fig. 4 shows a further embodiment of the invention. There are in thiscase three recesses formed in the anode, only the central and deepestrecess being mirrorsymmetrically formed relative to the cathode axis.Assuming an analogous symmetric effect in an electron optical lenssystem, as is created by the bars 20 relative to the bases 26 and whichis operatively a function of geometry and the potentials connected, thetwo walls 14 of the central recess will be likewise mirror-symmetricallyimpacted by the electron flow.

Contrary thereto, the walls 15 and 16 of the left recess and also thewalls 17 and 18 of the right recess are even with sufiicient symmetryoperation of their lens systems differently impacted by the electronflow. In the left recess, there will at any rate occur a strongerimpacting of the angularly extending wall 15 as compared with theimpacting of the oppositely disposed 'laterally' bulging wall 15 In-'corresp'ondi'ng' mannerjtlie inclined wan 1 8 wiu-Betmpaaed more"strongly than the less inclined wall1 7.:

In some special cases,

the radiation of the heat produced maybe increased by the provision, inknown manner, of cooling fins. This is indicated in connection with the'right recess by the cooling fin 19 extending from the impact wall .18.'similarfins may extend ,from the walls 15 and 16 of the lefthandjrecess. a The geometry of the electron'opticsfis'in Fig.1,4eifected by. the bases 26 in cooperationwith' th e oppositely extendingends of the elements '4 and the two bars 20. If an'electron opticalinfluence off'the electron impact distribution upon the individualimpact walls of a recess of a givenanode is desired, itma'y be obtainedby a nonsymmetric'ally operating electron optics. Such nonsymmetry maybe obtained, for example, in the position and form of the elements 4 andthe bars 20 or by different potential connections in the right and leftelements 4 and the two bars 20, which in such a case must not beoonductively connected. It is in this manner also possible to obtain inthe operation of a completely symmetrically designed tube, such as isfor example indicated in Fig. 3, nonsymmetry in the impacting of thefour impact walls 10, by not connecting the elements or members 4 onewith the other and directly with the bars C111, but placing them onsuitable fixed or functionally dependent potentials.

Figs. 5a and 5b show a further embodiment of the invention, Fig. 5aindicating a longitudinal section and Fig. 5b a transverse cross-sectionof a modified design of the recess formation. The allotting of the anoderecesses to the inner electrode system of the tube is here difierentthan in Figs. 2 to 4. As compared with these examples, the recesses aredisplaced by 90. The parts of the lens system designated by numeral 21are correspondingly displaced, such parts being formed as parts of anangular grid, as is particularly apparent from Fig. 5b. It is againimportant to provide for geometric conditions in the corresponding partsof the optics which is formed by the bars 21 in connection with therecess bases 27. In case the bases 27 extend perpendicular to the axis,the electron optically effective parts of the bars 2'1 will by theirparallel arrangement to the bases 27 also form wholly or partiallyclosed rings extending perpendicularly to the longitudinal cathode axis.

It is however also possible to proceed from a spiral thread line insteadof from the individual rings or ring sectors, in which case the bars 21will represent a spiral or be part thereof. In such a case, the recesseswill likewise form sectors of a spiral with the bases 27. Four recessesare shown in Fig. 5a, the eight impact walls thereof being indicated bynumerals 22, all of them being allotted to a single electron flow sectorof the inner system.

The electrodes of the inner electrode system 1, 2 and 3 are for the sakeof simplicity represented as corresponding to the system design shown inthe remaining figures. The tube in accordance with the number of itselectrodes would constitute a tetrode or a pentode. There is however noreason for limiting the invention to such multigrid tubes. Even in thepresence of such a number of electrodes, the grid 3 may, for example, beconnected with the recessed anode, as an auxiliary electrode, thuspermitting obtaining regarding the anode recesses, the action of atriode with electron optics. The grid 3 may also be eliminated,resulting in a simple triode with electron optics. It is furthermorepossible to use a directly heated cathode instead of the indirectly ovalcathode shown in the drawings.

Fig. 6 shows a further embodiment. The anode forms in this embodiment avariant of the anode shown in Fig. 3. It is produced by arranging theends (points) of the two recesses 12 (Fig. 3) in common, along thesymmetry plane formed by the cathode center and the bar 11, thusproducing for both recesses only one recess point; 'The rod"31" of"circularcross-section shown in Fig. 6, corresponds to the medianbase 13of the recesses 12 of Fig. 3. A cooling-effecting connection of the base81 with the common point of the two re'cesses mry in this case bedispensed'with. E'ach of the two recesses therefore partakes only withone side wall in receiving its allotted pairtofthe sector electron flow.The side walls 30 of the recesses combined at their ends, as shown inFig. 6, accordinglycorresponding to the two outer side walls/ 100f therecesses '12 of Fig. 3. Numerals 34 indicate cooling fins projectingfrom the wall 30. The bases 33 correspond to the bases 25"of Fig. '3.- I

i The member 31 shown in Fig. 6-which-forms a base forutilizing'thespace formed by the walls SQ-i'n'the manner of tworecesses-"need not be cross-sectionally circular; it may becross-sectional rectangular,- dropshaped or thelilie, as may be requiredor desired in ac cordance with the problem posed; 7 I ii i As in allembodiments according to the invention, the spacing between theindividual bases of the recesses from the inner system of a tube may bedifferent. In Fig. 6, there is provided an auxiliary electron opticaldistribution of the electron flow sector emanating from the innersystem. The geometric design of the optics is formed by the bases 33 and31 in connection with the electrode elements 4 and 32, analogous to theoptics of Fig. 3, the bar 32 of Fig. 6 corresponding thereby to the bar11 of Fig. 3.

Changes may be made within the scope and spirit of the appended claims.

I claim:

1. In an electron discharge tube having an inner system of electrodesincluding a cathode, electron streams emanating sector-like from saidinner electrode system, an anode adapted to prevent development of avirtual cathode and to dissipate by radiation heat developed due to theimact of electrons thereon, said anode having for each one of some ofsaid electron streams at least two operative recesses formed therein forthe reception of respective portions of the associated electron stream,said recesses being defined by wall means extending outwardly v indirections away from the cathode and angularly relative to the directionof the respective electron stream to relieve the regions extending aboutthe openings of said recesses substantially of the impact of electronsthereon and to form angularly outwardly directed heat radiating surfacesso as to effect cooling during the operation of the tube, andelectron-optical means interposed between the cathode and said anode tocontrol the electron flow into said recesses.

2. A structure and cooperation of parts according to olairn 1,comprising an electrode element disposed as seen in the direction ofelectron flow ahead of a recess, said electrode element constituting abase for deflecting the electron stream so as to form the effect of tworecesses.

3. A structure and cooperation of parts according to claim 1, comprisingauxiliary electrode means disposed 1alhead of said anode as seen in thedirection of electron 4. A discharge tube according to claim 1, whereinthe longitudinal dimensions of said recesses and the openings thereofextend in parallel with the longitudinal axis of said inner system.

5. A discharge tube according to claim 1, wherein said recesses are withtheir openings arranged annularly about the longitudinal axis of saidinner system.

6. A discharge tube according to claim 1, wherein the openings of saidrecesses are arranged in convolutions about the longitudinal axis ofsaid inner system.

7. A discharge tube according to claim 1, wherein the individualrecesses for an electron flow sector are disposed adjacent one another.

8. A discharge tube according to claim 7, wherein the: bases of twoadjacent recesses merge one into the other.-

9. A discharge tubeaccording to claim 8, wherein said bases are in theelectron flow direction relatively nar* row.

10. .A discharge tube according to claim 1, wherein the depth of saidrecesses exceeds the width of the open ings thereof.

'11. A discharge tube according to claim. 10, wherein said recessesareof different depth.

12. A discharge tube according to claim 10, wherein the openings of saidrecesses are-of difierent width.

13. A discharge tube according to claim 1, wherein said wall means areof arcuate shape.

14. A discharge tube according to claim 1, wherein said wall means areof irregular configuration.

15. A-discharge tube according to claim 1, wherein said 'wall means areshaped soas to effect subdivision of the .electron stream impactingthereon, and comprising an auxiliary electrode disposed ahead of saidanode.

l iefierences Cited in;the -ii.le of-this patent UNITED STATES PATENTS'Lederer Aug. ,1, Holst et a1. Oct. 27, Taylor Oct. 13, Haefi et a1.Dec. 17, Thompson Aug. 26, Haeif June 2, Litton Feb. 2, Van Over'beekFeb. 1, Skellett Feb. 19, Jonker Nov. 21, Sloan June 19, Sloan June 9,

